Depressed electron beam collector

ABSTRACT

A rugged electron beam collector structure for velocity modulation or other high power electron beam vacuum tubes is characterized by means for providing high electrical voltage insulation along a low thermal impedance heat flow path. The structure is constructed of stacked ceramic and metallic elements bonded together in a configuration providing improved tolerance to thermal and other shock mechanisms.

I United States Patent 1151 3,662,21 2 Rawls, Jr. 1451 May 9, 1972 [54] DEPRESSED ELECTRON BEAM 3,370,192 2/1968 Schwartz et al.. ..313/46 COLLECTOR 3,368,104 2/1968 McCullough..... ....315/5.38 2,325,865 8/1943 Litton ....315/5.38 1 Invent John Rawls, Archer, 2,853,641 9/1958 Webber 315/35 73 A z S R d C 2,955,225 10/1960 Sterzer ..315/3r5 1 ssgnee perry 0mm 3,500,096 3/1970 OLoughlin et al.. 315/538 x [22] Filed: July 15, 1 3,348,088 10/1967 Allen, Jr. ..313/30 [21] Appl' 54943 Primary Examiner-Herman Karl Saalbach Assistant Eraminer-Saxfield Chatmon, Jr. [52] US. Cl ..3l5/3.5, 315/538, 313/18, Attorney-S. C. Yeaton 313/30, 313/46 [51 Int. Cl. ..HOlj 25/34 [57] ABSTRACT [58] Flew of Search 15/35 538; 3 A rugged electron beam collector structure for velocity modu. lation or other high power electron beam vacuum tubes is characterized by means for providing high electrical voltage [56] References Cited insulation along a low thermal impedance heat flow path. The UNITED STATES PATENTS structure is constructed of stacked ceramic and metallic elements bonded together in a configuration providing improved 3,558,952 l/l97l Forbes ..313/46 tolerance to thermal and other Shock mechanisms 3,476,967 11/1969 Kreuchen ..315/5.38 X 3,471,739 10/1969 Espinosa ..315/5.38 X 9 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to means for improving the efiiciency and life-time of operation of beam power electron tubes and more particularly concerns a rugged, thermal-shock-proof electron beam collector for operation at depressed potentials in a velocity modulation type of high frequency power vacuum tube.

2. Description of the Prior Art Several types of high frequency power vacuum tubes exist that employ electron beams having high density electron currents driven at high velocities, such as velocity modulation tubes of the traveling wave and klystron types. In such devices production and acceleration of the electron beam occurs in a cathode-anode region and then the beam passes into a separate region in which its kinetic energy is used in part to amplify high frequency electromagnetic oscillations. In many early designs of such tubes, the electron beam, still having quite high kinetic energy, passes on out of the high frequency interaction structure and is dissipated in a third region as heat in a collector electrode held at the same potential with respect to ground as the interaction structure. The power wasted as heat directly causes low efficiency of operation and makes necessary the use of additional power in connection with special, often expensive and bulky, fluid cooling means to hold the temperature of the collector at a reasonable operating level. The high velocity electrons striking such a collector interior often also generate intensive X-radiation, making heavy and expensive shielding a health protection necessity.

It has been shown that the over-all efficiency of such beam tubes may be considerably increased by the use of specially designed electron beam collectors operated at potentials considerably below the potential of the high frequency interaction structure. Such collectors are known as depressed collectors and have permitted improved use of the total kinetic energy of the electron beam. Also, with greatly reduced heating of the collector, considerably less power is lost for cooling the collector and simple air cooling systems are often sufficient replacements for the previously needed complex liquid cooling systems. X-radiation is also reduced, permitting reduction in shielding against its destructive properties.

The depressed collector structure itself has a number of generally conflicting and difficult requirements which have, in the past, made its construction in satisfactory and inexpensive form not easily achieved. There is a large electrical potential difference between the high frequency interaction structure of the tube and the depressed collector and adequate high voltage insulation between the two elements must be provided. The electrical insulation structure must at the same time feature a low thermal impedance heat path from the core of the collector to the external heat sink. The metal and insulator parts of the collector system are subjected to high temperature-gradients and to high temperature-gradient rates of change or thermal shock. Repeated cycles from the zero to the high operating thermal gradient state must be tolerated if the vacuum tube is to exhibit satisfactory operating characteristics over a long-life period. Prior art designs for vacuum tubes with depressed collectors are notoriously prone to abrupt failures, even during manufacture as well as in the field, because of the above-mentioned problems. Rupture of bonds between insulator and metal parts is a common occurrence because of thermal shock in operation or because of simple mechanical shock during shipment or installation.

SUMMARY OF THE INVENTION The present invention is a rugged electron beam collector electrode system of the depressed potential type for application in velocity modulation vacuum tubes, such as traveling wave tubes and klystrons, and in other beam power tubes for improvement in their operational efficiency. The invention is characterized by the presence of a collector electrode system operated at potentials below the potential of the electron tube high frequency interaction structure so that a significant portion of the kinetic energy remaining in the electron beam as it exits from the high frequency interaction region may be recovered rather than lost as heat. The novel depressed electron beam collector electrode system is constructed of arrays of ceramic and metal elements bonded together in a manner providing reduced shear forces on ceramic to metal bonds and accordingly affording long-life operation of the vacuum tube assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory schematic representation of a velocity modulation tube employing a depressed collector electrode.

FIG. 2 is a cross section view of a preferred embodiment of the invention.

FIG. 3 is a cross section view similar to that of FIG. 2 of an alternative form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 represents schematically an electron beam type of velocity modulation tube embodying the electron beam collector of the present invention and showing operating circuit connections. While FIG. 1 schematically illustrates a helix traveling wave type of velocity modulation tube, it is to be recognized that other known high frequency, slow wave propagation elements may be substituted for the helix high frequency interaction circuit. Further, it is to be recognized that other types of high frequency interaction circuits may be substituted for the helix, including the cavity resonator systems characteristic of the klystron, such alternative arrangement being illustrated, for example, in US Pat. No. 3,172,004, entitled Depressed Collector Operation of Electron Beam Device," issued Mar. 2, 1965 to Messrs RJ. Von Gutfeld and CC. Wang, and also assigned to the Sperry Rand Corporation.

In FIG. 1, heater filament I is caused to heat the surface of the emitter cathode or electron beam forming means 2 by electrical current flowing from electrical source or battery 3. The cathode system is held at a negative potential with respect to ground by the cathode supply source 4. Consequently, a lineal electron beam 5, usually of circularly symmetric character, is projected through an aperture in grounded anode 6. Beam 5 flows in conventional energy exchanging relation through a grounded high frequency energy exchanging circuit device or helix 7 having respective input and output terminals 8 and 9, for example. Electrons passing out of helix 7, after exchanging energy with the traveling high frequency fields within helix 7, are collected by electron beam-collector electrode 10. Such is accomplished with collector 10 at a potential considerably depressed with respect to the ground potential of helix 7 by virtue of collector electrical potential source 11, one side of which is connected via lead 14 to collector 10 and the other via lead 12 to junction 13 between cathode supply source 4 and cathode 2.

As an example of operating potentials applied for operation of a traveling wave tube embodying the novel electron beam collector, cathode 2 may be operated at about -9,000 volts, anode 6 and helix 7 at ground potential, and collector electrode 10 at about 4,500 volts. The electrical potential values are to be taken merely as representative examples and are not necessarily intended to describe limiting or optimum values for operation of a traveling wave, klystron, or other beam power tube according to the invention.

FIG. 2 represents a preferred embodiment of the invention in which apertured diaphragm 20 may be spoken of as lying in a plane between old and new parts of a traveling wave amplifier tube embodying the invention. As is generally illustrated in the above mentioned Von Gutfeld et al., US. Pat. No. 3,172,004, diaphragm 20 and parts to the left of diaphragm 20 such as vacuum envelope 19 are conventional parts to be recognized as being assembled in the manner they are used in prior art traveling wave amplifiers. Parts to the right of diaphragm 20 make up the novel depressed collector structure of the present invention. It is to be observed that aperture 21 is aligned with the axis of the electron beam 5 of FIG. 1 and that beam 5, after having interacted with high frequency fields, such as those within helix 7 of FIG. 1, passes through aperture 21 of FIG. 2 into collector 10.

Electron beam 5 is actually stopped or collected by the generally symmetric interior walls of hollow electron beamcollector core 22, these inner walls being provided by cooperating axially aligned and axially extending interior sections forming wall portions 22a, 22b, 22c, and 22d. The core 22 may be made of a material such as oxygen-free copper. Wall portion 22a is in the form of a frustrum of a cone. it is joined at its small diameter end to a circularly cylindric wall portion 22b. Wall portion 22b is then joined through a short tapered step 22c to a second circularly cylindric wall portion 22d. The remote end of wall portion 22 is closed.

The collected electron beam current may be drawn from hollow core 22 via lead wire 14 which may also be comprised of copper and may be fastened by any of several known suitable means at 14a to the outer end of core 22. The collected current, as suggested in connection with FIG. 1, may be drawn off at a voltage which is negative with respect to the voltage on helix 7 and which is typically 40 to 60 per cent of the voltage supplied to cathode 2.

The progressively decreasing diameters of axially extending interior walls 22a, 22b, and 22d permit each such wall section to collect substantially the same fraction of the total electron beam current. Thus, the portions of the total remaining kinetic energy of the electron beam 5 converted to heat at wall sections 22a, 22b, and 22d are substantially equal. As a consequence, such heat is relatively evenly distributed along the length of core 22.

Core 22 is supported within an outer jacket or generally cylindric vacuum envelope wall 24, also constructed of a metal such as oxygen-free copper. One end of wall 24 is closed by diaphragm sealed at its periphery to wall 24, for example, by a circular brazed junction 26.

A drawn cup-shaped metal end wall or cap 25 is fastened at the opposite or outer end of wall 24 by a circular brazed vacuum tight junction 27. End wall or cap 25 is of sufficient volume to accommodate collector lead 14, which is formed with a right angle bend and projects out of the interior of cap 25 through insulator 29. Insulator 29 may be formed of any of several available ceramic materials having good high voltage insulation properties and adapted to form a vacuum tight seal with the metal of cap 24 at circular junction 30. Lead wire 14 is similarly sealed within a hole in insulator 29 at surface 28. Although other materials may be used, certain nickel-ironchromium alloys have been found to be useful for cap 25, since they are capable of being generated by drawing and since they readily form vacuum tight seals with ceramic materials.

From the foregoing, it is apparent that outer wall 24, cap 25, and insulator 29 complete the vacuum envelope means of the high frequency tube structure embodying the invention. Wall 24 has additional significant functions, in that it cooperates in the support of core 22 by means providing high electrical voltage insulation along radial, low thermal impedance, heat flow paths from core 22 to wall 24, as will be described. For dissipating such heat, wall 24 may, for example, be supplied with an enlarged flat or otherwise shaped portion 31 capable of being mounted on a suitable heat sink. It is clear that alternative external heat sink arrangements may readily be applied by those skilled in the art. It will also be seen that jacket wall 24 is arranged in an advantageous manner so that substantially all parts of the collector system are within its interior and therefore are not accessible, reducing the possibility of injury to persons by electrical shock or mechanical damage to the collector parts.

Heat is conducted directly in radial paths from the outer cylindric surface 34 of core 22 by a series of generally circular outwardly extending apertured fins 32 and 33 to 33d, the latter of which are fastened at substantially equal intervals to wall surface 34 as by brazing. Fin 32 is of a distinctive type, being formed integrally of oxygen-free copper with a discrete input section 35 of core 22, the apertured electron beam input section 35 being fastened by brazing to core 22 at junction 36. After the electron beam 5 flows through aperture 21 in diaphragm 20, it may tend to spread due to space charge effects while passing through the somewhat larger aperture 37 of input section 35 and into the interior of core 22.

Fins 32, 33, 33a, 33b, 33c, and 33d act as flexible support means and are spaced at substantially equal intervals, fins 33 to 33d being of generally similar structure. Typical of the latter group of fins is fin 33 which is seen to include an inner dished section 38 in the general form of a frustrum of a conical shell, the base of the conical shell being affixed to surface 34. The conical shell decreases in diameter in a direction away from the high frequency interaction circuit. As noted previously, the aperture wall 39 of dished section 38 may be brazed to the surface 34 of core 22. Fins 33a to 33d are similarly shaped and fastened and may include drilled-out holes, such as hole 40 in tin 32. Hole 40, for example, permits exhausting air from the interior of collector 10 when the vacuum tube is going through its final processing during manufacture. in a preferred form of the invention, however, hole 40 appears only in fin 32 and other means provide the rest of the desired exhaust channel. For example, a longitudinal slot 41 may be milled in the surface 34 of core 22 for the purpose, slot 41 extending from the vicinity of the end of core 22 supporting lead 14 to an interior portion of the tube served by hole 40 during exhaust. Slot 4] has the general appearance of a key slot such as might be milled in a machine shaft to permit use of a key to hold a gear or pulley in place.

A secondary array of seven generally similar apertured fins, made also of oxygen-free copper, extends cooperating support inward from the inner cylindric surface 24a of jacket wall 24, but does not directly contact wall 34 of core 22. The inner diameter of aperture 43 in the typical fin 42, for example, is considerably greater than the outer diameter of core 22, thus providing a substantial electrical clearance between core 22 and fin 42. Typical also of the array of flexible support fins means 42, 42a, 42b, 42c, 42d, 42e, and 42f is the dished portion 44 of fin 42 in the general shape of a frustum of a conical shell, the outer circular edge of portion 44 being brazed to the inner wall surface 24fruszrum or otherwise fastened thereto. The dished fin portions 44 may be equipped with drilled-out holes such as typically represented by hole 45 in fin 42 for the purpose of aiding evacuation of the vacuum envelope of the tube, including the interior of cap 25, during manufacture. Fins 42 to 42f are substantially equally spaced along wall surface 240 and are alternately interwoven with the array comprising fins 32 and 33 to 33d. The separations between the successive inward and outward extending fins are substantially equal.

Such equal spacings are designed to accommodate substantially equal width, spaced, flat-sided, insulator rings 46 to 46k between the flat sided parallel wall portions of the inward and outward extending arrays of fins. Rings 46 to 46k may be formed of any of several available ceramic material having good electrical insulation properties, suitable mechanical and thermal properties, and adapted to form a permanent shock resistant bond with the sheet copper of which the fins of the two fin arrays are constructed.

For example, flat-sided annular ring 46 is a representative element of the fin-insulator-fin structure. Ring 46 may be made of an alumina ceramic or of certain other well known refractory oxide materials, such as beryllium oxide. The annular flat sides 50a, 50b, of ring 46 are coated with nickel using a standard metal coating method. Surface 50a is placed on the flat annular face of inward extending fin 42. In turn, the outwardly extending fin 32 is placed on surface 501:. Additional conventional heating and other steps are taken to form permanent, mechanically sound bonds at surfaces 50a and 50b between ceramic ring 46 and the respective fins 42 and 32. A similar pair of bonds is found between ceramic ring 460 and fins 32 and 420, between ceramic ring 46b and fins 42a and 33, between ring 46c and fins 42b and 33a, and so forth on along the assembly to ceramic ring 46k whose flat sides are similarly joined to fins 33d and 42f.

Assembly of the collector may proceed piece by piece. On the other hand, one sub-assembly of collector 10 may be completed in a first step of one type and final assembly in a step of a second type. The state of the vacuum tube assembly art provides several alternative choices for suitable vacuum tube assembly programs. For example, a known ceramic-tometal bonding process may be used at a relatively high treatment temperature by first stacking the prepared ceramic spacers and fins and subjecting the stack as a sub-assembly to appropriate heat treatment for forming all metal-to-ceramic bonds simultaneously. The dished character of the fins is an aid to making proper relative locations of the fins and ceramic rings during stacking. The resultant sub-assembly may then be assembled with other parts, such as core 22, outer wall 24, and end cap 35, all in place with properly located rings of brazing material, such as an alloy of 35 per cent copper and 65 per cent gold or other suitable brazing material. The final assembly is then subjected to heating at a relatively low temperature to cause the braze joints to form, as by heating in a 3 hour program in a conventional belt conveyor brazing furnace. Brazing steps in assembling the collector may, of course, be performed at the same time as brazing operations on the cathode and interaction regions of the device are performed.

The composite depressed collector device is seen to have several significant characteristics not known in the prior art. Its construction provides adequate insulation of parts at high electrical potential from ground potential and at the same time features an adequately low thermal impedance path for heat flow to an external thermal sink. Problems with excessive relative differential thermal expansion of ceramic and metal parts are significantly reduced.

A primary beneficial feature of the invention lies in the presence of flexibility or relative freedom of movement of the parts of the assembly. For example, when the electron collector is cold, all collector parts are at substantially the same temperature. When beam power is turned on, the electron collector core 22 heats rapidly and increases in both radial and axial dimensions. The inwardly and outwardly extending arrays of dished fins are made of a soft flexible material, easily flexed, and allowing many repeated cycles of dimensional changes without placing destructive shearing stresses on the ceramicto-metal bonds. The fin configuration is such as to permit maximum axial translation of the outermost ceramic ring 46k with respect to the innermost ceramic ring 46, for instance, and also substantially to convert the tendency toward radial expansion of the assembly into axial expansion, thus further reducing shear stresses on ceramic-to-metal bonds. The progressive change in FIG. 2 in the angles of the dished portions 44 of the inwardly extending fins as one progresses from fin 42 to fin 42f contributes to this flexibility of the system. Among other advantageous features of the novel collector structure, such as relative freedom from exposure of personnel to high voltage parts, is the feature that all insulating outer surfaces of ceramic rings 46 to 46k are protected from exposure to moisture and dust. Similar features of the interior portions of the collector protect interior surfaces of ceramic rings 46 to 46k from degradation by deposition thereon of material evaporated or otherwise removed from the inner walls of core 22 by highly energetic electrons.

FIG. 3 illustrates an alternative depressed collector structure which displays an additional advantageous property of the invention; i.e., the arrangements of FIGS. 2 and 3 may be assembled largely of similar stock parts, a feature permitting significant cost saving since the total inventory of tube parts may consequently be reduced. It may be observed by inspecting FIGS. 2 and 3 that many of the same parts are employed in both structures and that the dimensions of most parts are the same. For example, the structure of FIG. 3 might be attached as a depressed collector to the same basic tube structure as is used with the structure of FIG. 2 wherever, for example, an application specifies need for a more efficient vacuum tube. To demonstrate the above considerations, FIGS. 2 and 3, while not necessarily actually representing scale drawings of optimum collectors, are drawn generally to the same scale and certain principal corresponding parts are identified with the same reference numerals. Features in FIG. 3 not found in FIG. 2 are identified with reference numerals in the I00 series.

For example, the unitary collector core 22 of FIG. 2 is replaced in FIG. 3 by a core 122 made up of three cooperating, axially aligned core portions 123, 123a, and 123b, respectively insulated one from the other by finite gaps of sufficient magnitude to prevent voltage breakdown across the gaps under vacuum operating conditions.

Core portion 123, for example, supplies an inner electron collecting surface 22a like surface 22a of FIG. 2. Core portion 123 is supported within jacket wall 24 by outwardly extending fins 32 and 33. As in FIG. 2, fins 32 and 33 are supported, in turn, by the agency of the array of ceramic rings 46 to 46k and by the array of inwardly extending fins 42 to 42]". Fin 33, and therefore core portion 123, has an appropriate voltage supplied to it via lead 124 which projects through vacuum sealed insulator 1240 in jacket wall 24.

Similarly, core portion 123a supplies an inner electron collecting surface 22b equivalent to surface 22b in FIG. 2. Core portion 123a is supported within jacket wall 24 by outwardly extending fins 33a and 33b. As in FIG. 2, fins 33a and 33b are supported, in turn, by the agency of the array of ceramic rings 46 to 46k and by the cooperating array of inwardly extending fins 42 to 42f. Fin 33b, and therefore the core portion 123a, has an appropriate voltage supplied to it via lead 125 which projects through vacuum sealed insulator 125a in jacket wall 24.

Finally, core portion I23b supplies the inner electron collecting surface 22d, which is analogous to surface 22d of FIG. 2. Core portion 123b is mounted within exterior wall 24 by outwardly extending fins 33c and 33d. As in FIG. 2, fins 33c and 33d are supported by the array of ceramic rings 46 to 46k and by the array of inwardly extending fins 42 to 42f. A suitable voltage is applied to core portion l23b via lead 14 in an arrangement similar to that of FIG. 2.

Assembly of the embodiment of FIG. 3 may proceed generally in the same fashion as the assembly of the form shown in FIG. 2. Particularly, it is seen that the inner surfaces 22a, 22b, and 22d of the successive core sections 123, 123a, and 123b are progressively smaller in diameter. Assembly may be aided, for example, by use of a jig with conventional locating steps to hold the core sections 123, 123a, and 12312 in proper relation during brazing of the core sections and the stacked ceramic ring assembly. The jig may be withdrawn when the brazing is completed and the resultant sub-assembly may then be brazed into envelope 24 in a separate operation. Alternative procedures will be apparent to those skilled in the vacuum tube art. I

The operating characteristics of the collector 10a of FIG. 3 are similar to those of the device 10 of FIG. 2. For the fin-insulator configuration is such as to permit maximum axial translation of the outermost ceramic ring 46k with respect to the innermost ceramic ring 46. Expansion, for example, when under rising temperature conditions is such as to maintain the gaps between core portions 123 and 123a and between core portions 123a and I23b safely above voltage breakdown values.

The embodiment of FIG. 3 has all of the various merits of that of FIG. 2, and combines with those the improvement in efficiency which is known to be achieved when a multiple stage collector with collecting electrodes or core portions at successively different potentials with respect to ground is employed. As is understood in the art, such improvement obtains because the multi-electrode system tends to overcome effects brought about by the velocity spread in the electrons being collected, a velocity spread inherently generated in the electron beam velocity modulation process. As in conventional practice with multiple section depressed collectors, the first core section 123 is operated at a potential which permits it to capture relatively low velocity electrons, the intermediate core section 123a at a potential permitting it to capture electrons of intermediate velocity, and the final core section 12312 at a potential for capturing the most energetic electrons. For example, in a typical operating tube with the helix 7 operated at ground potential, optimum efficiency is obtained by operating cathode 2 at 9,000 volts, core section 123 at -1,000 volts, core section 123a at 4,000 volts, and core section l23b at 6,000volts.

It is seen that the invention represents a significant improvement over the prior art, permitting realization of a rugged, shock proof electron beam collector for operation at depressed potentials. The rugged structure incorporates novel features assuring long life of a beam type of power tube under repeated cycles of operation without damage to cooperating metal and insulator parts of the collector and to bonds between those parts. Expansion effects are beneficially directed so that shear stresses on such metal-to-insulator bonds are significantly reduced, permitting long life of the vacuum tube structure even under severe operating conditions.

While the invention has been described in its preferred embodiment, it is to be understood that the words which have been used are words of description rather than limitation and that changes within the purview of the appended claims may be made without departure from the true scope and spirit of the invention in its broader aspects.

1 claim:

1. A lineal electron beam device comprising:

electron beam forming means,

high frequency circuit means in energy exchanging relation with said electron beam,

hollow electron beam-collector means spaced from said high frequency circuit means and having axially extending interior surface means for collecting said electrons and axially extending outer surface means,

vacuum envelope means supporting said electron beam forming means and said high frequency circuit means,

flexible support means within said vacuum envelope means for supporting said electron beam-collector means in electrically insulated, heat conducting relation within said vacuum envelope means, said flexible support means comprising:

first ring-shaped flexible metal fin means having first and second concentric portions,

second ring-shaped flexible metal fin means having third and fourth concentric portions, and

electric insulating, heat conducting means bonded to said first and third portions for forming therewith integral flexible support means.

2. Apparatus as described in claim 1 wherein said electron beam-collector means is coupled to electrical conductor means passing in insulated relation through said vacuum envelope means and adapted tdbe operated at a potential negative with respect to said high frequency circuit means.

3. Apparatus as described in claim 1 wherein said electrical insulating, heat conducting means is in the form of a ring with opposed flat parallel sides respectively bonded to said first and third portions of said flexible metal fin means.

4. Apparatus as described in claim 3 wherein said first portion is in the form of a truncated conical shell.

5. Apparatus as described in claim 3 wherein said fourth portion is in the form of a truncated conical shell.

6. Apparatus as described in claim 4 wherein the base of said truncated conical shell of said second portion is affixed to said vacuum envelope means.

7. Apparatus as in claim 5 wherein the base of said truncated conical shell of said fourth portion is affixed to said outer surface means.

8. A lineal electron beam device comprising:

electron beam forming means,

high frequency circuit means in energy exchanging relation with said electron beam,

hollow electron beam-collector means spaced from said high frequency circuit means and having an axially extending interior surface means for collecting said electrons and an axially extending outer surface means,

vacuum envelope means supporting said electron beam forming means and said high frequency circuit means,

flexible support means for supporting said electron beamcollector means within said vacuum envelope means,

said flexible support means being fixedly attached to said outer surface means and to said vacuum envelope means in heat exchanging relation therebetween,

said flexible support means comprising:

a first plurality of substantially regularly spaced fin means extending outwardly from said outer surface means,

a second plurality of substantially regularly spaced fin means extending inwardly from said vacuum envelope means in non-contacting interleaved relation with said first plurality and forming a plurality of substantially regular spaces between said interleaved elements, and

a third plurality of thermally conducting, electrically insulating means occupying at least a portion of each said spaces between said interleaved elements and bonded thereto for forming a plurality of radial, electrically insulated, thermally conducting paths between said electron beam-collector means and said vacuum envelope means,

at least first and second electrical conductor means passing in insulated relation through said vacuum envelope means, for supplying electric potentials to said electron beam-collector means,

said electron beam collector means comprising at least first and second electrically insulated axially aligned portions, and,

said first and second conductor means being adapted respectively to apply first and second potentials to said respective first and second aligned portions of said electron beam-collector means.

9. A lineal electron beam device comprising:

electron beam forming means,

high frequency circuit means in energy exchanging relation with said electron beam,

hollow electron beam-collector means spaced from said high frequency circuit means and having axially extending interior surface means for collecting said electrons and axially extending outer surface means,

vacuum envelope means supporting said electron beam forming means and said high frequency circuit means,

flexible support means within said vacuum envelope means for supporting said electron beam collector means, said flexible support means comprising:

a first plurality of substantially regularly spaced fin means affixed to and extending outwardly from said outer surface means,

a second plurality of substantially regularly spaced fin means afiixed to and extending inwardly from said vacuum envelope means in non-contacting interleaved relation with said first plurality and forming a plurality of regular spaces between said interleaved elements, and

a third plurality of thermally conducting, electrically insulating means occupying at least a portion of each of said spaces between said interleaved elements and bonded thereto for forming a plurality of radial, electrically insulated, thermally conducting paths between said electron beam-collector means and said vacuum envelope means. 

1. A lineal electron beam device comprising: electron beam forming means, high frequency circuit means in energy exchanging relation with said electron beam, hollow electron beam-collector means spaced from said high frequency circuit means and having axially extending interior surface means for collecting said electrons and axially extending outer surface means, vacuum envelope means supporting said electron beam forming means and said high frequency circuit means, flexible support means within said vacuum envelope means for supporting said electron beam-collector means in electrically insulated, heat conducting relation within said vacuum envelope means, said flexible support means comprising: first ring-shaped flexible metal fin means having first and second concentric portions, second ring-shaped flexible metal fin means having third and fourth concentric portions, and electric insulating, heat conducting means bonded to said first and third portions for forming therewith integral flexible support means.
 2. Apparatus as described in claim 1 wherein said electron beam-collector means is coupled to electrical conductor means passing in insulated relation through said vacuum envelope means and adapted to be operated at a potential negative with respect to said high frequency circuit means.
 3. Apparatus as described in claim 1 wherein said electrical insulating, heat conducting means is in the form of a ring with opposed flat parallel sides respectively bonded to said first and third portions of said flexible metal fin means.
 4. Apparatus as described in claim 3 wherein said first portion is in the form of a truncated conical shell.
 5. Apparatus as described in claim 3 wherein said fourth portion is in the form of a truncated conical shell.
 6. Apparatus as described in claim 4 wherein the base of said truncated conical shell of said second portion is affixed to said vacuum envelope means.
 7. Apparatus as in claim 5 wherein the base of said truncated conical shell of said fourth portion is affixed to said outer surface means.
 8. A lineal electron beam device comprising: electron beam forming means, high frequency circuit means in energy exchanging relation with said electron beam, hollow electron beam-collector means spaced from said high frequency circuit means and having an axially extending interior surface means for collecting said electrons and an axially extending outer surface means, vacuum envelope means supporting said electron beam forming means and said high frequency circuit means, flexible support means for supporting said electron beam-collector means within said vacuum envelope means, said flexible support means being fixedly attached to said outer surface means and to said vacuum envelope means in heat exchanging relation therebetween, said flexible support means comprising: a first plurality of sUbstantially regularly spaced fin means extending outwardly from said outer surface means, a second plurality of substantially regularly spaced fin means extending inwardly from said vacuum envelope means in non-contacting interleaved relation with said first plurality and forming a plurality of substantially regular spaces between said interleaved elements, and a third plurality of thermally conducting, electrically insulating means occupying at least a portion of each said spaces between said interleaved elements and bonded thereto for forming a plurality of radial, electrically insulated, thermally conducting paths between said electron beam-collector means and said vacuum envelope means, at least first and second electrical conductor means passing in insulated relation through said vacuum envelope means, for supplying electric potentials to said electron beam-collector means, said electron beam collector means comprising at least first and second electrically insulated axially aligned portions, and, said first and second conductor means being adapted respectively to apply first and second potentials to said respective first and second aligned portions of said electron beam-collector means.
 9. A lineal electron beam device comprising: electron beam forming means, high frequency circuit means in energy exchanging relation with said electron beam, hollow electron beam-collector means spaced from said high frequency circuit means and having axially extending interior surface means for collecting said electrons and axially extending outer surface means, vacuum envelope means supporting said electron beam forming means and said high frequency circuit means, flexible support means within said vacuum envelope means for supporting said electron beam collector means, said flexible support means comprising: a first plurality of substantially regularly spaced fin means affixed to and extending outwardly from said outer surface means, a second plurality of substantially regularly spaced fin means affixed to and extending inwardly from said vacuum envelope means in non-contacting interleaved relation with said first plurality and forming a plurality of regular spaces between said interleaved elements, and a third plurality of thermally conducting, electrically insulating means occupying at least a portion of each of said spaces between said interleaved elements and bonded thereto for forming a plurality of radial, electrically insulated, thermally conducting paths between said electron beam-collector means and said vacuum envelope means. 